1. Field of the Present Invention
The present invention relates to a process of producing liquid crystal panel containing liquid crystal dropping process, and more particularly, to a liquid crystal dropping process in which an isolation wall structure that is mutual-repulsive to liquid crystal is added and its producing method.
2. Description of Prior Art
Liquid crystal material is fluid, therefore it needs only very small external strength to move liquid crystal molecule and arrange in different ways. Take Nematic type liquid crystal for example, which is quite common, electric field can be used to change direction of liquid crystal molecule, and since the optic axis and the molecule axis of liquid crystal are in accord, thus causing optic effects. And if the arranging direction of liquid crystal is aligned properly in the beginning, then when the electric field imposed on liquid crystal is removed, on account of its own elasticity and viscosity, liquid crystal molecule will quickly go back to its original condition before the electric field is imposed on.
In prior injection of liquid crystal, vacuum liquid crystal injection process is usually used. Wherein, a LCD panel that has been cut and constituted is put into a vacuum sealant-up case, the LCD panel is then fixed up by a substrate, and liquid crystal is provided by a liquid crystal container under the substrate. Since the space in seal-up case is vacuum, liquid crystal can be drawn into LCD panel by capillarity and thus completes liquid crystal injection.
But this vacuum liquid crystal injection process takes very much time. Take a 15-inch LCD panel with a cell gap of 4.0 um for example: the vacuum liquid crystal injection process takes nearly 40 hours. And the liquid crystal injection process takes longer time as the size of LCD panel grows larger and as the cell gap shortens, thus causes a bottleneck in the process.
In order to eliminate this bottleneck in the process, a faster liquid crystal injection process has been developed, which is called One-Drop Filling technique. Wherein, a Uitra-Violet Rays sealant (abbr. UV sealant) is coated on a large-size substrate that has not been cut to form a plurality of close area that are similar to rectangles. Then liquid crystal is dropped directly on the substrate in controllable quantity by a dropping device, and the liquid crystal dropped in is confined in close areas formed by the UV sealant to prevent from overflowing. The substrate is then put in vacuum to be assembled with another substrate. After the assembly, the procedures of compression of sealant and curing of UV light irradiation are processed. The cell process is completed with cutting and sealing the cell. If a 15-inch LCD panel with a cell gap of 4.0 um is put under this ODF process, the time that the process takes about 1.5 hour shorter than before. And ODF process has nothing to do with the length of cell gap of LCD panel. Therefore, ODF technique has advantages such as simplification of the process, shorter time for the process, alienation of the process (that is to say, having nothing to do with the length of cell gap), less overflowing and wasting of liquid crystal, and fewer bubbles caused by incomplete liquid crystal injection, etc.
As is shown in FIG. 1 (excerpted from 1350-SID 01 DIGEST 56.2/S. Yamada), although ODF technique has the advantages said above, yet before liquid crystal 4 is dropped on substrate 1a or 1b, highly sticky sealant 3 must be coated on substrate 1a or 1b for sealing liquid crystal 4 and as adhesive in the assembly of LCD panel; and, at the same time, after the assembly of LCD panel, sealant 3 has to be put under irradiance of UV rays 60 for total curing. Therefore, when liquid crystal 4 is dropped on substrate 1a or 1b with ODF technique, liquid crystal 4 will contact with uncured sealant 3 and therefore makes Epoxy Resin molecule in sealant 3 spread into liquid crystal 4, contaminating and damaging liquid crystal 4. Especially in UV rays 60 irradiating and curing process, UV rays 60 will also irradiate some liquid crystal 4 that has contact with sealant 3 and thus causes more serious contamination of liquid crystal 4. This flaw will cause flaw of alignment of liquid crystal 4, worsening image quality of LCD panel, and also cause degradation of voltage retention of liquid crystal, causing flickers of image.
In order to prevent from contamination of liquid crystal 4 caused by adhesive fillet formed by uncured Epoxy Resin material in producing process of LCD panel, or contamination of spread of sealant molecule into liquid crystal, International Business Machine (IBM) has developed a technique using Barrier Fillet 2, as is shown in FIG. 2. Wherein, a barrier fillet 2 is deployed between adhesive fillet 2ab and liquid crystal 4 for isolating liquid crystal 4 from uncured sealant material 2ab to prevent liquid crystal 4 from being contaminated by uncured Epoxy Resin, referring [Panel Assembly for Liquid Crystal Displays Having Barrier Fillet and an Adhesive Fillet in the Periphery] in U.S. Pat. No. 006,219,126. The barrier fillet 2 described in the patent of IBM is made of compressive material, such as cured silicon elastomer. However, there will be new material cost and new procedures in this process, and in the UV rays irradiating and curing sealant process, liquid crystal cannot be shaded from UV rays and will still be irradiated directly and therefore causes defect in alignment of liquid crystal.